• Elastomers and Composites
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• 제49권1호
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• pp.73-81
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• 2014

칼날형 마모 마찰 시험기를 이용하여 NR배합고무의 마모 거동을 조사하였다. 온도, 하중, 그리고 회전속도를 변화시켜 마모속도에 미치는 영향과 열화된 배합고무의 마모 현상에 대해 평가하였다. 시편의 회전속도와 수직 하중이 증가할수록 마모속도가 증가하였다. 실험온도가 증가할수록 마찰계수가 감소하였고, 마모속도도 감소하였다. 마찰에너지와 마모속도 사이에 Power-Law 관계를 나타냈으며 마모속도는 열화에 의해 급격히 증가하였다. 시편의 마모패턴은 마모조건에 의해 영향을 받았으며 특히 수직 하중을 변화시켰을 때 마모융기(ridge)간격에 큰 변화를 보였다. 배합고무의 마모속도를 결정하는데 간헐적 마모손실 무게측정 대신 칼날형 마모시험기를 이용한 연속적인 마모이동거리측정으로 대체할 수 있음을 확인하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권4호
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• pp.1435-1442
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• 2015

Purpose: To study the patient load, treatment pattern, survival outcome and its predictors in patients with brain metastases treated by radiotherapy. Materials and Methods: Data for patients with brain metastases treated by radiotherapy between 2003 and 2007 were collected from medical records, the hospital information system database, and a population-based tumor registry database until death or at least 5 years after treatment and retrospectively reviewed. Results: The number of treatments for brain metastases gradually increased from 48 in 2003 to 107 in 2007, with more than 70% from lung and breast cancers. The majority were treated with whole brain radiation of 30 Gy (3 Gy X 10 fractions) by cobalt-60 machine, using radiation alone. The overall median survival of the 418 patients was 3.9 months. Cohort analysis of relative survival after radiotherapy was as follows: 52% at 3 months, 18% at 1 year and 3% at 5 years in males; and 66% at 3 months, 26% at 1 year and 7% at 5 years in females. Multivariate analysis demonstrated that the patients treated with combined modalities had a better prognosis. Poor prognostic factors included primary cancer from the lung or gastrointestinal tract, emergency or urgent consultation, poor performance status (ECOG 3-4), and a hemoglobin level before treatment of less than 10 g/dl. Conclusions: This study identified an increasing trend of patient load with brain metastases. Possible over-treatment and under-treatment were demonstrated with a wide range of survival results. Practical prognostic scoring systems to assist in decision-making for optimal treatment of different patient groups is absolutely necessary; it is a key strategy for balancing good quality of care and patient load.

• 한국물환경학회지
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• 제23권4호
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• pp.561-567
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• 2007

It is necessary to predict future water pollution sources in the establishment of Total Maximum Daily Load (TMDL) plan for watershed management. There are some difficulties and limits in estimating the pollution sources accurately since the prediction method is not firmly established. This study reviewed the existing methods of prediction and developed a technique characteristics. The characteristics were obtained by analyzing the change pattern of pollution sources by region and incorporated in the technique. A distinctive feature of the technique is to eliminate the influences of land use change included in the pollution source data of a region. The technique has been applied and tested. The test result showed the improvement on the prediction accuracy. A computer program was also developed for the easy application of the technique.

• 한국기계가공학회지
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• 제20권12호
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• pp.44-53
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• 2021

As environmental issues have emerged worldwide, emission gas regulations have been strengthened. In the construction machinery sector, studies have been actively conducted to utilize the power source of electric motors owing to the increasing demand for zero emissions. In this study, the gear specifications of an electric axle for construction machinery were selected by considering the specifications of the motor, gear tooth contact pattern, and face load factor. The gear strength evaluation was performed at the system level using the simulation model. The bending and contact strength of the spiral bevel gears and the bending strength of the planetary gear set showed a safety factor of 1 or more. However, the contact strength of the planetary gear set showed a safety factor of 0.92. Conservative results were derived by performing the analysis under the rated load condition of the motor. However, the ratio of the equivalent torque to the rated torque of the motor was 45% or less, hence, it was determined that no difficulties should arise regarding the durability of the axle.

• 한국의류학회지
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• 제45권3호
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• pp.453-463
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• 2021

The lengthwise and widthwise deformation of warp-knitted fabrics with different sizes and loading modes were evaluated. Moreover, five tricot samples cut in three directions were compared under four test conditions (A-D). In tests A and B, 500 and 250 g loads were applied on a layer of 20 × 20 and 5 × 10 cm² samples, respectively. In test C, a 20 × 20 cm² sample was folded in half over a rod, and 500 g load was applied to each half. In test D, a 20 × 20 cm² sample was sewn in a loop and subjected to a 500 g load. The lengthwise extension and widthwise contraction analysis results indicate that test B affords the largest values. However, analysis results of the warp-knitted fabric normalized through conversion to a 1 g load and 1 cm sample width indicate that the largest values are afforded for test D. Therefore, pattern reduction may vary depending on the measurement method and properties of the knitted fabric used for the compression wear production, causing variations in the finished product. Thus, an appropriate measurement method must be adopted based on the compression wear design and knitted fabric to be used.

• 대한토목학회논문집
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• 제37권2호
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• pp.269-276
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• 2017

본 연구는 철근콘크리트구조를 대신할 FRP-콘크리트 합성구조의 극한 휨 거동에 관한 것으로, FRP-콘크리트 합성보의 구조적 성능 및 거동 특성을 수치 해석적으로 규명하고자 범용 해석프로그램인 ABAQUS를 사용하여 외연적 비선형 유한요소해석을 실시하고 기 수행한 실험과 비교분석하였다. 콘크리트의 재료모델은 콘크리트 손상 소성모델을 사용하였으며, 콘크리트 압축응력은 유로코드를 사용하였다. 4가지 종류의 FRP-콘크리트 합성보에 대해 비선형해석을 수행하고 극한하중 및 균열 형태를 비교 분석하였다. 본 모델의 경우 극한 하중 및 균열 형태를 잘 모사할 수 있었기 때문에 앞으로 다양한 FRP-콘크리트 합성구조의 정밀한 구조거동 해석 및 분석에 사용 가능할 것으로 판단된다.

• 한국농공학회지
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• 제17권3호
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• pp.3878-3884
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• 1975

This study was carried out to develop the throw-in type thresher with its size as small as possible. Developing the smallest possible size of the throw-in type thresher has been very important to increase mobility and to reduce the machine price. The thresher that developed for this purpose was tested as to threshing and separation performance for the samples collected in eight catch boxes under the concave while threshing. The amount of grain collected in each compartments was measured and the threshing and separating pattern along the total span of the threshing drum was determined. The performance of separating and threshing units of the test thresher and threshing loss was evaluated by use of the developed grain separating apparatus and the method for measuring the grain separating performance of threshers. The results are summarized as follows; 1. The unthreshed grain (drum losses) and semi-threshed grain did not appeared at all throughout the treatments. 2. When threshed by making use of the developed throw-in type thresher, the threshing grain loss at about 25 per cent grain moisture was about one-half when threshed at about 18 per cent grain moisture. 3. And its grain separating loss in higher feed rate was decreased in comparison with that of lower feed rate. These results suggests that the throw-in type thresher may be suitable for wet threshing and for higher feed rate of threshing. 4. Above 60 per cent of total grain passing through concave fell through the screen within a scant 30 cm from the feeding inlet. This threshing pattern may suggest that major threshing action may be finished before about one third of cylinder length. The required separating load extended over the whole drum span is so defferent that separating elements should be redesigned so as to accomodate this variable pattern of separation load. 5. It was apparent from the experiment that the length of the threshing drum of the throw-in type thresher could be reduced from 1285mm to about 1050mm without increasing grain separation loss greatly.

• 전기전자학회논문지
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• 제23권1호
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• pp.322-325
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• 2019

비간섭 전력부하 감시 알고리즘은 메인선의 총 전력 사용량만으로 개별 전기 기기들의 전력 사용량을 추론할 수 있다. 이런 알고리즘을 개발하기 위해서는 개별 기기의 전력사용 패턴 데이터와 이들 기기의 다양한 조합 전력사용 패턴 데이터가 필요하다. 본 논문에서는 스마트팜용 비간섭 전력부하 감시 알고리즘개발에 필요한 전력사용 패턴 데이터 취득시스템 개발방법을 제시하였다. 데이터 취득시스템은 매초마다 개별 전기 기기들의 전력 사용량과 다양한 조합의 시나리오에 따른 전력 사용량을 동시에 측정할 수 있도록 되어 있다. 측정된 데이터는 LTE 망을 통하여 스마트팜 외부에서 원격으로 모니터링이 가능하며, 측정된 데이터는 외부 서버에 저장된다.

• 화약ㆍ발파
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• 제23권2호
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• pp.45-56
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• 2005

본 연구에서는 철근 콘크리트 기둥 발파시 수직하중과 철근의 영향에 따른 파쇄형태 및 파쇄체적에 대해 축소모형실험을 수행하였다. 수직하중이 증가할수록 수직하중에 의한 수직방향의 인장균열 및 철근에 의한 수직방향의 균열이 발생하였으며, 2.0톤에서는 수직방향의 인장균열이 철근에 의한 수직방향의 균열보다 우세하게 나타났다. 또한 수직하중이 증가할수록 수직방향의 인장균열이 우세하여 철근의 휨정도는 감소하였다. 발파공수가 증가하여도 수직하중에 따른 평균 파쇄체적은 크게 증가하지 않았으며, 이는 철근이 파쇄체적에 영향을 미치는 것으로 판단된다. 따라서 콘크리트 기둥 발파시 수직하중은 콘크리트의 파쇄형태와 철근의 휨정도에 중요한 영향을 미치며 철근은 파쇄체적에 영향을 미친다. 그러므로 철근 콘크리트 기둥 발파해체시 수직하중과 철근의 영향에 따라 천공패턴 및 발파패턴을 조절해야 한다.

• 설비공학논문집
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• 제27권6호
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• pp.283-292
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• 2015

A model of apartment heating load in a district heating system could be useful in the management and utilization of energy resources, since it could predict energy usage and so could assist in the efficient use of energy resources. The heating load in a district heating system varies in a highly nonlinear manner and is subject to many different factors, such as heating area, number of people living in that complex, and ambient temperature. Thus there are few published papers with accurate models of heating load, especially in domestic literature. This work is concerned with the modeling of apartment heating load in a district heating system in winter, using the reduced least square support vector machine (LS-SVM), and with the purpose of using the model to predict heating energy usage in domestic city area. We collected 23,856 pieces of data on heating energy usage over a 12-week period in winter, from 12 heat exchangers in five apartments. Half of the collected data were used to construct the heating load model, and the other half were used to test the model's accuracy. The model was able to predict the heating energy usage pattern rather accurately. It could also estimate the usage of heating energy within of mean absolute percentage error. This implies that the model prediction accuracy needs to be improved further, but it still could be considered as an acceptable model if we consider the nonlinearity and uncertainty of apartment heating energy usage in a district heating system.